Front light and method for producing same, reflective display device provided with front light, and electronic equipment provided with reflective display device

Abstract

A front light ( 1 ) includes a light source ( 8 ), a light guide plate ( 9 ), and a plurality of dots ( 4 ) that are provided on a surface of the light guide plate ( 9 ), which surface faces a light exit surface of the light guide plate ( 9 ). Each of the plurality of dots ( 4 ) includes (i) a light reflective layer ( 2 ) for reflecting light toward the light guide plate ( 9 ), and (ii) a dark layer ( 3 ) for absorbing light, the dark layer completely covering the light reflective layer ( 2 ) so as to be in contact with the light guide plate ( 9 ) without any gap between the light guide plate ( 9 ) and the dark layer ( 3 ).

The invention claimed is:  
     
       1. A front light, comprising:
 a light source for emitting light outward; 
 a light guide plate for guiding the light of the light source; and 
 a plurality of dots, provided on a surface of the light guide plate, which surface faces a light exit surface of the light guide plate, 
 each of the plurality of dots including (i) a light reflective layer for reflecting light, the light reflective layer being provided so as to be in contact with the light guide plate and (ii) a dark layer for absorbing light, the dark layer completely covering an upper surface and a side surface of the light reflective layer so as to be in contact with the light guide plate without any gap between the light guide plate and the dark layer. 
 
     
     
       2. The front light as set forth in  claim 1 , wherein:
 the plurality of dots are arranged on the light guide plate at a constant ratio of occupied area of dots per certain unit area. 
 
     
     
       3. The front light as set forth in  claim 2 , wherein:
 the light reflective layers of the respective plurality of dots are smaller in size as the plurality of dots are located closer to the light source, whereas the light reflective layers of the respective plurality of dots are larger in size as the plurality of dots are farther away from the light source. 
 
     
     
       4. The front light as set forth in  claim 2 , wherein:
 the plurality of dots are arranged, in a matrix manner, (i) at regular intervals in a row direction of the plurality of dots and (ii) at regular intervals in a column direction of the plurality of dots. 
 
     
     
       5. The front light as set forth in  claim 4 , wherein:
 each of the plurality of dots, and corresponding two of the plurality of dots, located closest to the each of the plurality of dots, are apexes of an equilateral triangle. 
 
     
     
       6. The front light as set forth in  claim 4 , wherein:
 in a case where the light guide plate is viewed from a light exit surface side, the row direction is at an angle ranging from 5° to 85° with any of four sides of the light guide plate. 
 
     
     
       7. The front light as set forth in  claim 4 , wherein:
 the regular intervals in the row direction is (n+0.2) to (n+0.8) times as large as intervals at which pixels are arranged where n is an integer. 
 
     
     
       8. The front light as set forth in  claim 1 , wherein:
 the dark layers of the respective plurality of dots are each smaller in size than a pixel. 
 
     
     
       9. The front light as set forth in  claim 1 , wherein:
 each of the dark layers is not more than 20 μm in size. 
 
     
     
       10. The front light as set forth in  claim 1 , wherein:
 the light source is provided on any of four side surfaces other than (i) the light exit surface of the light guide plate and (ii) the surface of the light guide plate which surface faces the light exit surface, and 
 a side surface of the four side surfaces, on which side surface the light source is not provided, is a light reflective surface. 
 
     
     
       11. The front light as set forth in  claim 1 , wherein:
 the light reflective layers of the respective plurality of dots are respective light scatterers. 
 
     
     
       12. The front light as set forth in  claim 1 , wherein:
 convexoconcave surfaces are provided, on the light guide plate, for the respective light reflective layers, and 
 the convexoconcave surfaces are coated with a metal material so as to serve as the respective light reflective layers. 
 
     
     
       13. The front light as set forth in  claim 1 , wherein:
 each of the light reflective layers is provided by stacking, on the light guide plate, a light scatterer and a metal material in this order. 
 
     
     
       14. The front light as set forth in  claim 1 , wherein:
 recesses are provided, in the light guide plate, for the respective light reflective layers, and 
 the light reflective layers are provided in the respective recesses. 
 
     
     
       15. The front light as set forth in  claim 1 , wherein:
 a functional layer is provided on the surface of the light guide plate on which surface the plurality of dots are provided. 
 
     
     
       16. A reflective display device, comprising:
 a front light recited in  claim 1 ; and 
 a display panel which is provided on a light exit surface side of the light guide plate. 
 
     
     
       17. The reflective display device as set forth in  claim 16 , wherein:
 a space between the front light and the display panel is filled with a low-refractive resin whose refractive index is not more than 1.45. 
 
     
     
       18. The reflective display device as set forth in  claim 16 , wherein:
 the light source of the front light is capable of emitting different-colored beams of light, and 
 the reflective display device displays an image by causing the light source to sequentially emit the different-colored beams of light. 
 
     
     
       19. An electronic device, comprising a reflective display device recited in  claim 16 . 
     
     
       20. The electronic device as set forth in  claim 19 , wherein:
 the front light can be attached to or detached from the reflective display device.